A corpora



Dec. 4, 1928.

- H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Feb. 5, 1926 INVENTORQ Patented Dec. 4-, 192.8.

UNi'i-ED STATES PATENT OFFIE.

HOWARD A. THOMPSON, OF EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

RAILWAYTRAFFIC-CONTROLLING APPARATUS.

Application filed February 5, 1926, Serial No. 86,306. Renewed April 25, 1928.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus of the type comprising traflic governing means controlled by current flowing in 5 the track rails.

I will describe one form of railway traflic controlling apparatus embodying my invention, and will then pointout thenovel features thereofin claims.

The accompanying drawing is a diagrammatic viewillustrating one form of railway trafiic controlling apparatus embodying my invention.

Referring to this drawing, the reference characters 1 and 1 designate the track rails of a stretch ofrailway track over which traffic normally moves in the direction. indicated by the arrow; These trackrails are divided, a. by means of insulated joints2, intoa pluralit y of. succcssive 't-rack Sections .A B, BC, etc. Each track section is provided ,with a track transformer designateclith'e reference character T with a suitahlevdistinguishing exponent and having ,a' secondary 25 connected across the vrails adjacent the exit. end or the associated section in series withl areactor. 6.. The primaryi 2fi of each track. transformer T islconstantlyk supplied -,with alternating cum-matron s'econdar,yf27 of an associated line transformer designated by the reference'jcharacter L with an exponent corresppndingto. the location, The pr mary 28 of each line transformer L is constantly supplied with alternating current from a suitable source suchas an alternator Q, over linewires 3 and 3f. .11

Each track ,sectioiris also provided with two track r claysdesignated by the reference characters .E,.: PQ l3h w @XP'O- ncnts corresponding tothe'locationand connectedin parallel across the-ra ls of the associated section, adjacent thej entrance end thereof. Air asymme ric illnitlfi i f'fi lbf' 'n i e yp "A re sh w t ad way ignal is located adjacent the entrance ,posedh etweeneach;relay D: and the rails of the. associated section, and 'asimllar asymmetrical-unit is t rpe e l t r i .nals designated by the reference; character S'with an exponent corresponding-"to the 10- rclay E. and the rails of ithe; corresponding section. I The asymmetrical units-.4 and 5 are oppositely disposed soas topermit current v of one polarity but not of the other toflow through one trackrelay and to permit current of the other polarity but not of the first polarity to fiow through the other track relay, v That is tosay, during one-half of each natin'g current of the sect-ionv'f proceed, caution or c 'cle of the alternating current supplied to tie rails of a section, by the transformer '1 associated therewith, current flows through relayD for that section and not through the associated relay E. During the other half of each cycle current flows through relay E and not through relay D.

The asymmetrical units 4 and 5Imay be of any suitable type, such for. example, as the units disclosed'and claimed in an application for Letters Patent'of the United States, Serial No. 1111, filed January 7,1925, by Lars O. Gr ondahl, for uni-directional current carrying'devices. I

It willflbe clear from the foregoing that each track section is provided with a track 'circuitcomprisingthe secondary 25 of a track transformer T,' a'reactor 6, the rails 1 and 1 inf the section inser'ies, and two track relays 7D and E with their; associated asymmetrical units cdnnejcted 'in 'parall el.'j When the track section'lsunoccupied, the alternating current jsilp'pliejdthereto by;' the track transformer energizes both"t he t'rackirelays.D' and E.

When the section i'sfbccupie'd,however, cur- ..rent is shunted'awayl from it he tr'ack relays j'by't hewheels'andi aniljesfof the'train and relay D d E? re. both dc nergiz d. a

advantage"of;trackf circuits en'ibodying inye'ntlonis thatfs' tra'y direct currentsfln the track rails'can'not energize both the track relays. 'Any stray direct' ,current in the rails of a tracmeai'onta n flow through o ly. n qr the trackrelaysfchnnected with that section, and is 'pr'evente'd'fjfron flowing through the other relay by the asymmetrical unit associated "with such 'relay; fwill be plain therefore that the track" 'I T'elays D' and ,E..-wi 1- 0t be n r d Qnly wh n filteris being suppliechto'itlie rails The trackf iii hich I described be used tocontrol ti'afiic governing means end of each track sectionfffEacli' of; the: sigca tion and in tlieiormhereshown comprises a semaphore signal capable of indicating stop. Each track section is provided also With-a line relay designated by. the" reference charac'ter with an appropriate distinguishing I exponent. Referring particularly to relay K, this relay is energized only when the track relays for sections AB and BC are all energized, the circuit for this relay passing from secondary 27 of line transformer L", through wires 29 and 30 front Contact 31 of relay I'l wire 32, front contact of relay D, wire 3-3 front contact of relay E", wire 35, front contact 37 of relay D, wire 38, winding of relay K and wires 39, 21. and ll back to secondary 2T of transforn'i'er L The circuit for each of the remaining line relays K is similar to that just traced for linerelay K.

Each signal S is controlled by the track relays and by the line relay associated therewith. Referring particularly to signal S, this signal is provided wit-h a caution circuit which may be traced from secondary 27 of transformer L through wires 7 and 8, front contact 9 of relay D, wire 10, front contact 11 of relay E", wires 12 and 13, operating mechanism of signal S, wires 14, 15 and 16, front contact 17 of rel'ayE, wire 18, front contact 19 of relay D and wires 20, 21 and 21", back to secondary 27 of transformer L".

.This circuit is closed only when track rela s D and E are energized, under which con itions, if relay K" is open, signal S displays a caution indication. (See signals). If

- line relay K is also energized, current flows from secondary 27 of transformer L",

"th'r'o'u '11 wires 7 and 8, front contact 9 of relay wire 10, frontcontact 11 of relay E, wires 12 and'22, front contact 23 of relay K", wire 24, operating mechanismof si S wires 14, 15 and 16, fipnt'eon tact 17 of relay E, wire l8, front contact -19 of relay D, and wires 2 0, 21 and 21 back to secondmy 27 of transformer LE. When this circuit is closed, signal sfdisp'la-ys a-proceed' indication. It will be seen that when either relay 'D 'or E is de energizled, ,both the-caution and proceed circuits just are open so that the signal S indicatesstop, and furthermore, the closing of back Contact 9 of relay D or' of back contact 11 of relay E will short circuit the operating mechanism of signal S.

- In tlie" stretch illustrated in the drawing,

- the section immediately to the right of point C is occupied by atrainindirted diagrammatically at V. Current is therefore shunted away from relays D -and E and these relays are de-energized, Relay K is therefore also tie-energized, and" signal S indicates stop. Current issup'plied to section BC by transformer T and relays D and E are both energized. Relay K is de-energized howeye'r, itscircuit be'inq open at front contacts 33 and 31 of relays and E9, respectively The caution circuit for signal S is therefore closed but the proceed circuit for this signal is open at front contact 23 of relay K. Signal S therefore displays a caution indianalv cation. The alternating current supplied lo section AB by transformer 'l energizes relays D and E. Relay K" is also energized over front cont-acts of relays D", 15:, D" and E and the proceed circuit for signal S is therefore closed so that this signal displays a proceed indication.

It should be pointed out that stray direct current in section AB or l3C can have no effect upon the apparatus because the tmck relays for these sections are already energized by alternating current supplied thereto by the track transformers. Furthermore, stray direct current in the section to the. right of point C can pick up only one of the track relays D or IC depending upon thepolarity of such stray current, and this cannot cause signal S to indicate caution or proceed. In other words, the apparatus herein described is absolutely immune to the effect of stray direct current in the trackway, because such direct current cannotcause a less restrictive condition of the trafiic governin" means cont-rolled by the track circuits.

Alt ough I have herein shown and described only one form of railway traffic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims withoutdeparting from the spirit and scope of my invention.

tion, two relays connected with the rails of said section, asymmetrical units associated with said relays for permitting current of one polarity but not of the other to pass through one relay and for permitting current of the other clarity but not of the first polarity to pass t tough the other relay, and tia' C relays.

2. In combination, a .section of railway track, a source of alternating. current conected with the rails of said section, tv lays connected with the rails of said section, asymmetrical units associated with said rclays for permitting current. of one polarity but not of the other to pass through one relay and for permitting current of the other pole rity but not of the first polari ty to pass through the other relay, a third relay controlled by said two relays, and by traffic conditions in advance of said section, and traffic gmerniu means cont-rolled by all three relays.

3. In combination, a plurality of successive sections of railway track, means for supplying alternating current to the rails of each such section, two track relays connected with the rails of each such section, asymmetrical units associated with the track relays for each governing means controlled by said section for permitting current of one polarity to pass through one track relay and for permitting current of the other polarity but not the first to pass through the other relay, a line relay.for each section controlled by the two track relays for the associated section and by traffic conditions in advance of said section, and traffic governing means for each section controlled by the associated track relays and line relay.

4. In combination, a plurality of successive sections of railway track, means for supplying alternating current to the rails of each such section, two track relays connected with the rails of each such section, asymmetrical.

units associated with the track relays for each section for permitting current of one polarity to pass through one track relay and for permitting current of the other polarity but not the first to pass through the other relay, a line relay for each section controlled by the track relays for the associated section and by the track relays for an adjacent section, and trafiic governing means for each section controlled by the associated track relays and line relay.

5. In combination, a plurality of successive sections of railway track, means for supplying alternating current to the rails of each such section, two track relays connected with the rails of each such section, asymmetrical units associated with the track relays for each section for permitting current of one polarity to pass through one track relay and for permitting current of the other polarity but not the first to pass through the other relay, 9. line relay for each section, a circuit for each line relay including afront contact on each track relay for the associated section and a front contact on each track relay for an adjacent section, a trackwa signal, a caution circuit for said signal inc uding a front contact on each associated track relay, and a proceed circuit for each signal including a front contact on the associated line'relay and a front contact on each associated track relay.

6. In combination, a section of railway track, a source of alternating current constantly connected with the rails of said section, two relays connected withthe rails of said section, asymmetrical units associated with said relays for permitting current of one polarity but not of the other to pass through one relay and for permitting current of the other polarity but not of the first polarity to pass through the other relay, a trackway signal for said section, a caution circuit for said signal including a front contact on each such relay, and means for shunting said signal when either said relay is de-energized.

In testimony whereof I affix my signature.

HOWARD A. THOMPSON. 

